639529891 has 36 divisors (see below), whose sum is σ = 868779408. Its totient is φ = 458092800.

The previous prime is 639529843. The next prime is 639529897. The reversal of 639529891 is 198925936.

It is not a de Polignac number, because 639529891 - 2⁷ = 639529763 is a prime.

It is not an unprimeable number, because it can be changed into a prime (639529897) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 2653531 + ... + 2653771.

Almost surely, 2^639529891 is an apocalyptic number.

639529891 is a deficient number, since it is larger than the sum of its proper divisors (229249517).

639529891 is a wasteful number, since it uses less digits than its factorization.

639529891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 524 (or 272 counting only the distinct ones).

The product of its digits is 1049760, while the sum is 52.

The square root of 639529891 is about 25288.9282295632. The cubic root of 639529891 is about 861.5628203406.

The spelling of 639529891 in words is "six hundred thirty-nine million, five hundred twenty-nine thousand, eight hundred ninety-one".